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<a name="Looking-up-or-entering-a-string"></a>
<h4 class="subsection">2.18.2 Looking up or entering a string</h4>
<a name="index-bfd_005fhash_005flookup"></a>
<p>The function <code>bfd_hash_lookup</code> is used both to look up a
string in the hash table and to create a new entry.
</p>
<p>If the <var>create</var> argument is <code>FALSE</code>, <code>bfd_hash_lookup</code>
will look up a string.  If the string is found, it will
returns a pointer to a <code>struct bfd_hash_entry</code>.  If the
string is not found in the table <code>bfd_hash_lookup</code> will
return <code>NULL</code>.  You should not modify any of the fields in
the returns <code>struct bfd_hash_entry</code>.
</p>
<p>If the <var>create</var> argument is <code>TRUE</code>, the string will be
entered into the hash table if it is not already there.
Either way a pointer to a <code>struct bfd_hash_entry</code> will be
returned, either to the existing structure or to a newly
created one.  In this case, a <code>NULL</code> return means that an
error occurred.
</p>
<p>If the <var>create</var> argument is <code>TRUE</code>, and a new entry is
created, the <var>copy</var> argument is used to decide whether to
copy the string onto the hash table objalloc or not.  If
<var>copy</var> is passed as <code>FALSE</code>, you must be careful not to
deallocate or modify the string as long as the hash table
exists.
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